[PATCH] D111401: [LoopIdiom] Fix store size SCEV type.

[Clement Courbet via Phabricator via llvm-commits]

courbet created this revision.
courbet added reviewers: lebedev.ri, nikic.
Herald added a subscriber: hiraditya.
courbet requested review of this revision.
Herald added a project: LLVM.

We were using the type of the loop back edge count to represent the
store size. This failed for small loop counts (e.g. in the added test,
the loop count was an i2).

Use the index type instead.

Fixes PR52104.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D111401

Files:
  llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
  llvm/test/Transforms/LoopIdiom/memset-pr52104.ll


Index: llvm/test/Transforms/LoopIdiom/memset-pr52104.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopIdiom/memset-pr52104.ll
@@ -0,0 +1,43 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -basic-aa -loop-idiom < %s -S | FileCheck %s
+
+define void @f(i32* nocapture nonnull align 4 dereferenceable(20) %0, i32 %1) local_unnamed_addr #0 align 32 {
+; CHECK-LABEL: @f(
+; CHECK-NEXT:    [[TMP3:%.*]] = trunc i32 [[TMP1:%.*]] to i2
+; CHECK-NEXT:    [[TMP4:%.*]] = zext i2 [[TMP3]] to i64
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i32, i32* [[TMP0:%.*]], i64 [[TMP4]]
+; CHECK-NEXT:    [[SCEVGEP1:%.*]] = bitcast i32* [[SCEVGEP]] to i8*
+; CHECK-NEXT:    [[TMP5:%.*]] = sub i2 -1, [[TMP3]]
+; CHECK-NEXT:    [[TMP6:%.*]] = zext i2 [[TMP5]] to i64
+; CHECK-NEXT:    [[TMP7:%.*]] = shl nuw nsw i64 [[TMP6]], 2
+; CHECK-NEXT:    [[TMP8:%.*]] = add nuw nsw i64 [[TMP7]], 4
+; CHECK-NEXT:    call void @llvm.memset.p0i8.i64(i8* align 4 [[SCEVGEP1]], i8 0, i64 [[TMP8]], i1 false)
+; CHECK-NEXT:    br label [[TMP9:%.*]]
+; CHECK:       9:
+; CHECK-NEXT:    [[TMP10:%.*]] = phi i32 [ [[TMP14:%.*]], [[TMP9]] ], [ [[TMP1]], [[TMP2:%.*]] ]
+; CHECK-NEXT:    [[TMP11:%.*]] = and i32 [[TMP10]], 3
+; CHECK-NEXT:    [[TMP12:%.*]] = zext i32 [[TMP11]] to i64
+; CHECK-NEXT:    [[TMP13:%.*]] = getelementptr inbounds i32, i32* [[TMP0]], i64 [[TMP12]]
+; CHECK-NEXT:    [[TMP14]] = add nsw i32 [[TMP10]], 1
+; CHECK-NEXT:    [[TMP15:%.*]] = and i32 [[TMP14]], 3
+; CHECK-NEXT:    [[TMP16:%.*]] = icmp eq i32 [[TMP15]], 0
+; CHECK-NEXT:    br i1 [[TMP16]], label [[TMP17:%.*]], label [[TMP9]]
+; CHECK:       17:
+; CHECK-NEXT:    ret void
+;
+  br label %3
+
+3:                                                ; preds = %3, %1
+  %4 = phi i32 [ %8, %3 ], [ %1, %2 ]
+  %5 = and i32 %4, 3
+  %6 = zext i32 %5 to i64
+  %7 = getelementptr inbounds i32, i32* %0, i64 %6
+  store i32 0, i32* %7, align 4
+  %8 = add nsw i32 %4, 1
+  %9 = and i32 %8, 3
+  %10 = icmp eq i32 %9, 0
+  br i1 %10, label %11, label %3
+
+11:                                               ; preds = %4
+  ret void
+}
Index: llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -786,7 +786,8 @@
 
     bool IsNegStride = StoreSize == -Stride;
 
-    const SCEV *StoreSizeSCEV = SE->getConstant(BECount->getType(), StoreSize);
+    Type *IntIdxTy = DL->getIndexType(StorePtr->getType());
+    const SCEV *StoreSizeSCEV = SE->getConstant(IntIdxTy, StoreSize);
     if (processLoopStridedStore(StorePtr, StoreSizeSCEV,
                                 MaybeAlign(HeadStore->getAlignment()),
                                 StoredVal, HeadStore, AdjacentStores, StoreEv,


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D111401.378171.patch
Type: text/x-patch
Size: 2914 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20211008/0a368e27/attachment.bin>